Cable guidance for pick & place robots: safely guided despite a rotating axis

Light and flexible rotating energy supply ensures gentle cable guidance to the gripper

Pick & place robots are playing an increasingly important role in automated processes, for example on assembly lines. With its EXPT, the automation specialist Festo offers a highly precise and dynamic solution for this. With up to 150 picks per minute, the robot works reliably in continuous operation. For this, a safe and gentle feeding of the cables to the gripper had to be guaranteed. The special feature: an additional axis, which allows the gripper to rotate, led to increased wear of the cables. With a special energy chain for tight installation spaces and dynamic applications, including a rotation module, the cables are now safely guided in high angles of rotation.

Problem

Festo SE & Co. KG is a leading provider of automation solutions for processes and entire production plants. The manufacturer also includes its universal parallel robot "EXPT" in its extensive product portfolio. The pick-and-place robot based on a tripod works with high performance and precision and manages up to 150 picks per minute. Its design and control system enable flexible and cross-application use. In this way, a convenient implementation can also be achieved in applications with several robots in the production line.
At the lower end of the robot, where the gripper is located, an A5 axis was to be implemented, which should enable the gripper to rotate quickly and precisely. A special challenge here was the safe and gentle guidance of the cables to the rotating axis. Because with a high number of cycles and continuous operation, 360° rotations in less than a second, speeds of up to 7m/s and accelerations of up to 60m/s2, there is a heavy load on all cables, which can lead to high wear.

Solution

For the cable guidance, we suggested a rotary energy supply to the customer, i.e. an energy chain with a reverse bend radius including a rotation module. To be more precise, the cables run in an energy chain of the E2 micro series. Running in a special rotation module, the energy chain can also achieve the desired high angle of rotation.
The design of the cable guidance enables several advantages for the pick-and-place robot: as the extremely lightweight allows the robot to be highly flexible and move quickly, the failure rate of the cables leading to the A5 axis has been significantly reduced.
So far, there has not been a solution on the market for such a cable feed to the rotary axes, which is why the development work between the Festo engineers and our cable specialists was characterised by a very close exchange. During this collaboration, the specific cables to be considered for this application were also selected. Among other things, the manufacturer relies on chainflex® control cables for high loads in moving applications. So that Festo can save itself the harnessing, the automation specialist ordered the energy chain directly with the cables drawn in and ready for connection as a so-called readychain®.

Profile

  • What was needed: E2-micro series energy chain, designed as Reverse Bend Radius energy chain and moving in a rotation module, delivered pre-assembled as readychain®
  • Requirements: gentle cable guidance to the rotating axis with a high number of cycles, under continuous operation, with 360° rotations in less than one second, speeds of up to 7m/s and accelerations of up to 60m/s2
  • Industry: robotics; pick and place robots
  • Success for the customer: the energy chain with a reverse bend radius achieves high angles of rotation and, thanks to its being extremely lightweight, supports the high flexibility of the robot and fast movements. The failure rate of the cables leading to the A5 axis has been significantly reduced.